A. Field of the Invention
The present invention relates to methods for protecting the corners of rectangularly-shaped picture frames from impact damage during shipping. More particularly, the invention relates to a method and apparatus for attaching protective covers to the corners of picture frames.
B. Description of Background Art
Picture frames for holding and displaying paintings, photographs, diplomas, certificates and similar flat articles are manufactured in prodigious quantities worldwide. Although picture frames vary in shape and construction details, most frames have a rectangular plan view shape. Moreover, the structure of most picture frames consists essentially of four straight channel members or moldings, each having an inner channel that intersects channels of adjacent members at a ninety degree angle. Four such channel members fastened together form a rectangular ring-shaped frame. The channels or recesses in the moldings comprise spaces for receiving a rectangularly-shaped flat display piece such as a photograph or painting, and sometimes, a backing panel, mat and protective cover glass.
Picture frames of the type described above are made from a variety of materials including, wood, metal and plastic. Whatever material the frame is made of, the geometry of a rectangular picture frame dictates that it have four peripheral members of generally uniform thickness and joined to each other at fourty-five degree mitre angles to form ninety degree corners. These corners protrude, and are therefore highly subject to breakage, denting or cosmetic damage during shipment. Accordingly, most picture frames, whether empty or occupied, are fitted with some sort of corner protectors during shipment. Such corner protectors are usually made of a relatively inexpensive recyclable material such as cardboard or polystyrene foam. Typical corner protectors of this type are disclosed in U.S. Pat. Nos. 3,955,677, 4,598,825, and 5,447,233. Other patents, related to protecting corners of objects during shipping include U.S. Pat. No. 4,407,898. Also, U.S. Pat. No. 5,255,458 discloses a three-dimensional picture corner and U.S. Pat. No. 4,787,553 discloses a corner fastening device.
In addition to the above-referenced patents related to corner protectors and the like, a variety of machines for bending sheet metal or cardboard of the type used for corner protectors have been disclosed in the following U.S. Pat. Nos.: 4,132,102, 4,585,432, 4,713,957, 4,857,038, 4,956,961, and 5,184,998. However, the present inventor is unaware of any machines for automatically attaching corner protectors to picture frames. The present invention was conceived to provide that capability.